The present invention relates to a miniaturized switching power supply regulator and its control circuitry, and more particularly to one in which the drive from the output amplifier is controlled at a pre-programmed level.
A major difficulty in the miniaturization of the switching power supply control is the heat dissipation from losses within the power supply circuit. These losses result from a number of factors, and efforts have been made to control them. One significant factor which has not been heretofore recognized is the need for control of the gate drive levels of the final output power unit of the switching power supply, viz., a power FET. It is desirable to reduce the size of the switching power supply to approximately the size and shape of a standard IC, so that little circuit board space is required, and connection of the switching power supply is made readily by means of terminals or pins, and conventional assembly equipment may be used for assembling the power supply with the other circuit components. However, a problem in reducing the size of switching power supplies to this level is that the heat dissipation is so great as to put a lower limit on the size which can be achieved, due to inefficiencies in the circuit. Specifically, when the gate is driven beyond the point at which the drain switches, excess energy is dissipated.
One of the inefficiencies contributing to excess heat within the circuit is excess drive applied to the gate of the final control FET.
It is accordingly desirable to provide a mechanism for limiting the gate drive of this unit, so that excess power dissipation can be reduced.